Astronomy Look-alikes, No. 82

Posted in Astronomy Lookalikes with tags , on January 2, 2013 by telescoper

The resemblance between wacky comedian Richard Bower and Durham University astrophysicist Prof. Kenny Everett is too strong to be disguised even by a flamboyant wig. Surely there must be a family connection?

Lookalike

Science Propaganda

Posted in Science Politics, The Universe and Stuff with tags , , on January 2, 2013 by telescoper

I thought I’d do a quick rehash of an old post which is vaguely relevant to the still simmering controversy generated by the Cox-Ince editorial I blogged about before Christmas.

The legitimate interface between science and society has many levels to it. One aspect is the simple need to explain what science tells us about the world in order that people can play an informed part in our increasingly technological society. Another is that there needs to be encouragement for (especially young) people to study science seriously and to make it their career in order to maintain the supply of scientists for the future. And then there is the issue of the wider cultural implications of science, its impact on other belief-systems (such as religions) other forms of endeavour (such as art and literature) and even for government.

I think virtually all scientists would agree with the need for engagement in at least the first two of these. In fact, I’m sure most scientists would love to have the chance to explain their work to a lay audience, but not all subjects are as accessible or inspirational as, say, astronomy. Unfortunately also, not all scientists are very good at this sort of thing. Some might even be counter-productive if inflicted on the public in this way. So it seems relatively natural that some people have had more success at this activity than others, and have thus become identified as “science communicators”. Although some scientists are a bit snobby about those who write popular books and give popular talks, most of us agree that this kind of work is vital for both science and society.

Vital, yes, but there are dangers. The number of scientists involved in this sort of work is probably more limited than it should be owing to the laziness of the popular media, who generally can’t be bothered to look outside London and the South-East for friendly scientists. The broadsheet newspapers employ very few qualified specialists among their staff even on the science pages so it’s a battle to get meaningful scientific content into print in the mass media. Much that does appear is slavishly regurgitated from one of the press agencies who are kept well fed by the public relations experts employed by research laboratories and other science institutes.

These factors mean that what comes out in the media can be a distorted representation of the real scientific process. Heads of research groups and laboratories are engaged in the increasingly difficult business of securing enough money to continue their work in these uncertain financial times. Producing lots of glossy press releases seems to be one way of raising the profile and gaining the attention of funding bodies. Most scientists do this with care, but sometimes the results are ludicrously exaggerated or simply wrong. Some of the claims circulating around the time the Large Hadron Collider was switched on definitely fell into one or more of those categories. I realise that there’s a difficult balance to be struck between simplicity and accuracy, and that errors can result from over-enthusiasm rather than anything more sinister, but even so we should tread carefully if we want the public to engage with what science really is.

The Cox-Ince editorial is refreshingly clear about the limitations of science:

Science is a framework with only one absolute: all opinions, theories and “laws” are open to revision in the face of evidence. It should not be seen or presented, therefore, as a body of inviolate knowledge against which policy should be judged; the effect of this would be to replace one priesthood with another. Rather, science is a process, a series of structures that allow us, in as unbiased a way as possible, to test our assertions against Nature.

However, there is still far too much science reporting that portrays as facts  ideas and theories which have little or no evidence to support them. This isn’t science communication, it’s science propaganda and I think too many scientists go along with it. There’s a difficult balance to be struck, between engaging the public with inspirational but superficial TV programmes and explaining the intellectual struggles that science really involves.  Give the public the latter without any of the former and they’ll surely switch off!

Most worryingly is the perceived need to demonstrate black-and-white certainty over issues which are considerably more complicated than that. This is another situation where science popularisation becomes science propaganda. I’m not sure whether the public actually wants its scientists to make pronouncements as if they were infallible oracles, but the media definitely do. Scientists sometimes become cast in the role of priests, which is dangerous, especially when a result is later shown to be false. Then the public don’t just lose faith with one particular scientist, but with the whole of science.

Science is not about certainty. What it is a method for dealing rationally with uncertainty. It is a pragmatic system primarily intended for making testable inferences about the world using measurable, quantitative data. Scientists look their most arrogant and dogmatic when they try to push science beyond the (relatively limited) boundaries of its applicability and to ride roughshod over alternative ways of dealing with wider issues including, yes, religion.

I don’t have any religious beliefs that anyone other than me would recognize as such. I am also a scientist. But I don’t see any reason why being a scientist or not being a scientist should have any implications for my (lack of) religious faith. God (whatever that means) is, by construction, orthogonal to science. I’m not at all opposed to scientists talking about their religion or their atheism in the public domain. I don’t see why their opinions are of any more interest than anyone else’s in these matters, but I’m quite happy to hear them voiced.

This brings us to the question, often raised by hardline atheists, as to whether more scientists  should follow Richard Dawkins’ lead and be champions of atheism in the public domain. As a matter of fact, I agree with some of Dawkins’ agenda, such as his argument for the separation of church and state, although I don’t feel his heavy-handed use of the vitriol in The God Delusion achieved anything particularly positive (except for his bank balance, perhaps). But I don’t think it’s right to assume that all scientists should follow his example. Their beliefs are their business. I don’t think we will be much better off if we simply replace one set of priests with another. In this respect I wholeheartedly agree with Peter Higgs who has recently described Dawkins as “embarrassing”.

So there you have my plea for both public and scientists to accept that science will never have all the answers. There will always be “aspects of human experience that, even in an age of astonishing scientific advance, remain beyond the reach of scientific explanation”.

Can I have the Templeton Prize now please?

The Cox-Ince affair rumbles on..

Posted in Science Politics with tags , , on January 1, 2013 by telescoper

The Cox-Ince controversy rumbles on, apparently…

Ken's avatarOpen Parachute

Popular science presenters like Brian Cox are sometimes criticised by colleagues suffering from a bit of professional jealousy – although it’s a lot better than in the old days. I think most scientists today recognise the need for good science communication with the public – who, after all, are financing our science through the taxation system.

Brian Cox and his mate Robin Ince wrote a recent New Statesman editorial promoting a better understanding of the nature of science and its role in public decision-making (see Politicians must not elevate mere opinion over science). It made some good points – but upset some people. The jealousy this time seems to come from a few historians and sociologists – and not scientists themselves.

I think their criticism reveals an unfortunate attitude towards the scientific process, or indeed a misunderstanding of that process. Nevertheless, the debate does reveal some aspects of the…

View original post 2,382 more words

Resolution

Posted in Jazz with tags , , , , on January 1, 2013 by telescoper

Yesterday I happened to be listening to the classic album A Love Supreme made by the John Coltrane quartet in 1964. Since the second of the four “movements” (for what of a better word) of this work is called Resolution, I thought it would be a good thing to post on New Year’s Day to welcome everyone to 2013!

A Love Supreme is one of my favourite jazz albums, not only because it’s glorious music to listen to but also for its historical importance. Shortly after making this record Coltrane comprehensively changed his musical direction, abandoning many of the structures that underpinned his earlier work and adopting an approach heavily influenced by the free jazz of the likes of Ornette Coleman and, especially, Albert Ayler. Not everyone likes the music Coltrane made after he made that transition (in 1965) but having taken his earlier style to such a high peak as A Love Supreme he and the rest of the band no doubt felt they couldn’t go any further in that direction.

There are glimpses of the later freer approach in the third track, Pursuance, when the drum and saxophone interchanges between Elvin Jones and Coltrane threaten to break the regular tempo apart, and on this (the second) track Resolution, when McCoy Tyner abandons his usual single-note lines in favour of much more complex chordal improvisations. I think Coltrane’s solo on the last track, Psalm, is entirely improvised and , accompanied by Jones’ rising and falling drum rolls, it acquires a hauntingly solemn atmosphere which makes the hairs stand up on the back of my neck every time I hear it. What a fantastic drummer Elvin Jones was.

But I haven’t got time to analyse the whole album – another’s words are in any case no substitute for listening to this masterpiece yourself – so I’ll just mention that Resolution is based on an 8-bar theme that’s very reminiscent of the theme Africa featured on Africa/Brass made a couple of years earlier. To me it sounds like Coltrane is just itching to cut loose on this track. His saxophone tone has a harder edge than usual for that period, giving the piece an anguished, pleading feel. Elvin Jones is also magnificent, his polyrhythmic accents spurring Coltrane to a climactic solo.

The intensity of Resolution ignites an even more dramatic onslaught on the next track, Pursuance, basically a blues taken at a very fast tempo, before the mood changes completely for the final part, Psalm. And all this builds from the opening track, Acknowledgement, which closes with the whole group chanting the words A Love Supreme in unison to a simple four-note figure stated at the opening of the piece.

Four tracks amounting to just over 30 minutes of music, but a masterpiece by any standards.

Happy New Year!

2012 in review

Posted in Uncategorized on December 31, 2012 by telescoper

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

About 55,000 tourists visit Liechtenstein every year. This blog was viewed about 460,000 times in 2012. If it were Liechtenstein, it would take about 8 years for that many people to see it. Your blog had more visits than a small country in Europe!

Click here to see the complete report.

A Little Bit of Gravitational Lensing

Posted in The Universe and Stuff with tags , , , , , on December 30, 2012 by telescoper

I thought I’d take a short break from doing absolutely nothing to post a quick little item about gravitational lensing. It’s been in my mind to say something about this since I mentioned it in one of the lectures I gave just before Christmas, but I’ve been too busy (actually too disorganized) to do it until now. It’s all based on a paper posted to the arXiv in December which was led by Jo Woodward (née Short) who did her PhD with me in Cardiff and is now in a postdoctoral research position in Durham (which is in the Midlands). The following pictures were take from her paper.

This figure shows the geometry of a gravitational lens system: light from the source S is deflected by the gravitational potential of the lens L so that an image I appears at a position on the sky which is different from the actual position when viewed by the observer O:

lensing_1
There’s a critical radius (which depends on the mass and density profile of the lens) at which this can lead to the formation of multiple images of the source. Even if multiple images are not resolved, lensing results in an increase in the apparent brightness of the source.

A great deal of cosmological information can be gleaned statistically from lensing  with even limited knowledge of the properties of the source and lens populations and with incomplete information about e.g. the actual angular deflection produced by the lens or the lens mass. To illustrate this, just consider the expression for the differential optical depth to lensing (related to the probability that a source at redshift z_s is lensed by an object at redshift z_l
lensing_2

The first two terms are cosmological, accounting geometrical and expansion effects. Roughly speaking, the larger the volume out to a given redshift the higher the probability is that a given source will be lensed. The third term involves the mass function of lens systems. In the framework of the standard cosmological model this can be computed using Press-Schechter theory or one of the variations thereof. According to current understanding, cosmological structures (i.e. galaxies and clusters of galaxies) form hierarchically so this mass function changes with redshift, with fewer high mass objects present at high redshift than at low redshift, as represented in this picture, in which masses are given in units of solar masses, the colour-coding representing different redshifts:
lensing_3

The last term represents the lensing cross-section of an object with a given mass. This depends on the internal structure of the lens – an object in which the mass is highly concentrated produces  lensing effects radically different from one that isn’t. Two simple models for the mass distribution are the singular isothermal sphere (SIS) and the Navarro-Frenk-White profile (NFW). The latter is thought (by some) to represent the distribution of cold dark matter in haloes around galaxies and clusters which is more diffuse than that of the baryonic material because it can’t dissipate energy which it needs to do to fall into the centre of the object. The real potential of a galaxy in its central regions could be more like the SIS profile would predict, however, because baryons outweigh dark matter there.

Now time for a bit of historical reminiscence. In 1997 I published a book with George Ellis in which we analysed the evidence available at the time relating to the density of matter in the Universe. It was a little bit controversial at the time, but it turns out we were correct in concluding that the density of matter was well below the level favoured by most theorists i.e. only about 20-30% of the critical density. However we did not find any compelling evidence at that time for a cosmological constant (or, if you prefer, dark energy). Indeed one of the strongest upper limits on the cosmological constant came from gravitational lensing measurements, or rather the dearth of them.

The reason for this negative conclusion was that, for a fixed value of the Hubble constant,  in the presence of a cosmological constant the volume out to a given redshift is much larger than if there is no cosmological constant. That means the above integral predicts a high probability for lensing. Surveys however failed to turn up large numbers of strongly-lensed objects, hence the inference that the universe could not be dominated by a cosmological constant. This is, of course, assuming that the other terms in the integral are well understood and that the reason significant numbers of lensed systems weren’t found wasn’t just they are tricky to identify…

Meanwhile, huge advances were made in other aspects of observational cosmology that established a standard cosmological model in which the cosmological constant makes up almost 75% of the energy budget of the Universe.

Now, 15 years later on, enter the Herschel Space Observatory, which turns out to be superb at identifying gravitational lenses.  I posted about this here, in fact. Working in the far-infrared makes it impossible to resolve multiple images with Herschel – even with a 3.5m mirror in space, λ/D isn’t great for wavelengths of 500 microns! However, the vast majority of sources found during the Herschel ATLAS survey with large fluxes at this wavelengths can be identified as lenses simply because their brightness tells us they’ve probably been magnified by a lens. Candidates can then be followed up with other telescopes on the ground.  A quick look during the Science Demonstration Phase of Herschel produced the first crop of firmly identified gravitational lens systems published in Science by Negrello et al..  When the full data set has been analysed there should be hundreds of such systems, which will revolutionize this field.

To see the potential (no pun intended) of this kind of measurement, take a look at these five systems from the SDP set:

lensing_4

These systems have measured (or estimated) source and lens redshifts. What is plotted is the conditional probability of a lens at some particular lens redshift, given the source redshift and the fact that strong lensing has occurred. Curves are given for SIS and NFW lens profiles and everything else is calculated according to the standard cosmological model. The green bars represent the measured lens redshifts.  It’s early days, so there are only five systems, but you can already see that they are pointing towards low lens redshifts, favouring NFW over SIS;  the yellow and light blue shading represents regions in which 68% of the likelihood lies.  These data don’t strongly prefer one model over the other, but with hundreds more, and extra information about at least some of the lens systems (such as detailed determinations of the lens mass from deflections etc) we should be able  to form more definite conclusions.

Unfortunately the proposal I submitted to STFC to develop a more detailed theoretical model and statistical analysis pipeline (Bayesian, of course) wasn’t funded. C’est la vie. That probably just means that someone smarter and quicker than me will do the necessary…

R.I.P. Tony Greig

Posted in Cricket with tags , , , on December 29, 2012 by telescoper

Shocked and saddened by news of the death of former England cricket captain Tony Greig, at the age of only 66.  He was a controversial character, but a fine all-rounder and skipper as a player, and also part of the finest comedy double-act in cricket history (with Geoffrey Boycott) when he became a commentator:

Winter landscape, with rocks

Posted in Poetry with tags , on December 29, 2012 by telescoper

Water in the millrace, through a sluice of stone,
plunges headlong into that black pond
where, absurd and out-of-season, a single swan
floats chaste as snow, taunting the clouded mind
which hungers to haul the white reflection down.

The austere sun descends above the fen,
an orange cyclops-eye, scorning to look
longer on this landscape of chagrin;
feathered dark in thought, I stalk like a rook,
brooding as the winter night comes on.

Last summer’s reeds are all engraved in ice
as is your image in my eye; dry frost
glazes the window of my hurt; what solace
can be struck from rock to make heart’s waste
grow green again? Who’d walk in this bleak place?

by Sylvia Plath (1932-1963)

The Planck Rumour Mill

Posted in The Universe and Stuff with tags , , , , on December 28, 2012 by telescoper

I gather the internet is crawling with people searching for rumours about the Planck mission. It would obviously be entirely inappropriate for me to direct my readers to any website where they might obtain access to confidential information about this experiment, the results from which are embargoed until well into the New Year. So naturally that’s what I’m going to do. Well, blog traffic doesn’t generate itself does it?

As a Telescoper exclusive I am able to offer you a sneak preview of the top secret Planck data well in advance of official release. If you want to see what Planck scientists have been looking since Planck was launched in 2009, just click here.

Around the old home

Posted in Biographical with tags , , , on December 28, 2012 by telescoper

Back from a brief Christmas visit up North I thought I’d post a few snaps I took on our traditional Boxing Day spin around Northumberland. The weather wasn’t exactly marvellous, but it did at least stop raining for a while when we reached Amble  so we got out of the car and went for a stroll around the little harbour…

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Although it was a cold and wet day it wasn’t too windy. They must be tough fishermen who go out into the North Sea in those little boats, but they’re friendly folk too – waving to us landlubbers as they came in and out of the harbour.

On the way home we stopped at Benwell, not a picturesque place but the part of Newcastle in which I was brought up. I’ve posted about the little house where my first memories live here, and there’s an old photograph of it here:

The house itself (ours was the one on the left on this picture) was built of brick but to the left hand side you can just see a stone wall. The two cottages were demolished some time ago, along with Pendower School which was behind them as viewed from the picture. The whole area has now been covered with new houses, but for some reason they left the stone wall. I hopped out of the car to take a couple of pictures, as this is all that remains of the first place I can remember living. These were both taken from Ferguson’s Lane, which is immediately behind the stone wall I mentioned earlier, i.e. to the left of the two cottages in the old photograph.

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In the second picture you can see the filled in outlines of the door which led to our backyard (on the right) and (on the left) the holes through which the coalman used to deliver the coal that was the only form of heating in the house. There was no central heating and no heating at all upstairs, incidentally, so we had very cold bedrooms in winter!